U.S. patent number 6,901,788 [Application Number 10/423,308] was granted by the patent office on 2005-06-07 for apparatus and method for determining oil change based upon oil viscosity.
This patent grant is currently assigned to Delphi Technologies, Inc.. Invention is credited to Taeyoung Han, Mark K Krage, Yingjie Lin, Su-Chee Simon Wang.
United States Patent |
6,901,788 |
Han , et al. |
June 7, 2005 |
Apparatus and method for determining oil change based upon oil
viscosity
Abstract
An oil change sensing system for an internal combustion engine,
having an oil pressure sensor adapted to provide an oil pressure
signal to an engine control module; an oil temperature sensor
adapted to provide an oil temperature signal to the engine control
module; wherein the engine control module comprises an algorithm
which determines the oil's viscosity by using the measured oil
temperature and oil pressure and the determined oil viscosity and a
fresh oil viscosity are used to determine whether the oil is in a
preferred operating range.
Inventors: |
Han; Taeyoung (Bloomfield
Hills, MI), Wang; Su-Chee Simon (Troy, MI), Krage; Mark
K (Troy, MI), Lin; Yingjie (El Paso, TX) |
Assignee: |
Delphi Technologies, Inc.
(Troy, MI)
|
Family
ID: |
32962457 |
Appl.
No.: |
10/423,308 |
Filed: |
April 25, 2003 |
Current U.S.
Class: |
73/53.05;
73/114.55; 73/114.56; 73/114.57; 73/54.01; 73/54.02 |
Current CPC
Class: |
F01M
11/10 (20130101); F01M 2011/1446 (20130101); F01M
2011/1473 (20130101); F01M 2011/148 (20130101) |
Current International
Class: |
F01M
11/10 (20060101); G01N 033/26 (); G01N
011/00 () |
Field of
Search: |
;73/54.01,54.02,53.05,53.01,54.42,61.78,61.76,117.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
S Manco, Nervegna, M. Rundo, G. Armenio, C. Pachetti and R.
Trichilo, Gerotor Lubricating Oil Pump for IC Engines, 1998 Society
of Automotive Engineers, Inc., pp. 1-17..
|
Primary Examiner: Larkin; Daniel S.
Attorney, Agent or Firm: Funke; Jimmy L.
Claims
What is claimed is:
1. An oil change sensing system for an internal combustion engine,
comprising: an oil pressure sensor adapted to provide an oil
pressure signal to an engine control module; an oil temperature
sensor adapted to provide an oil temperature signal to said engine
control module; and a sensor for providing a signal to the engine
control module, the signal being indicative of the rpm of the
engine; wherein said engine control module comprises an algorithm
which determines the oil's viscosity by using the measured oil
temperature, oil pressure, and the engine rpm and the determined
oil viscosity and a fresh oil viscosity are used to determine
whether the oil is in a preferred operating range.
2. The oil change sensing system as in claim 1, further comprising
a look up table having oil viscosity measurements as a function of
oil pressure.
3. The oil change sensing system as in claim 2, further comprising
a means for determining whether the oil of the engine has been
changed and updating the look up table by measuring and recording
the viscosity of the oil in the engine after the oil in the engine
has been changed wherein the recorded viscosity becomes said fresh
oil viscosity.
4. The oil change sensing system as in claim 3, further comprising
a means for determining whether a relief valve of an oil pump of
the engine is closed.
5. The oil change sensing system as in claim 3, further comprising
a means for determining whether the oil in the engine is in an
unregulated flow.
6. The oil change sensing system as in claim 3, wherein the
algorithm determines whether a relief valve of an oil pump of the
engine is closed by measuring the oil pressure and the oil
temperature.
7. The oil change sensing system as in claim 3, wherein the
recorded viscosity is only obtained if the oil changing system has
determined that the oil of the engine has been changed.
8. The oil change sensing system as in claim 2, wherein said look
up table includes oil pressure measurements as a function of oil
temperature and engine rpm.
9. A method for indicating whether the oil of an engine should be
changed, comprising: determining if the flow of the oil is
unregulated, by measuring the oil pressure and the oil temperature;
retrieving a used oil viscosity from a look up table; and using
said used oil viscosity and a fresh oil viscosity to determine
whether the oil's viscosity is in a preferred range.
10. The method as in claim 9, wherein said fresh oil viscosity is
stored in said look up table.
11. The method as in claim 9, wherein the steps of the method are
performed by an algorithm resident upon a microprocessor of an
engine control module.
12. The method as in claim 9, further comprising a step for
determining whether the oil in the engine has been changed and if
so said fresh oil viscosity is updated by obtaining a fresh oil
viscosity from the look up table by measuring the oil pressure as a
function of oil temperature and engine rpm, the engine rpm being
determined by a sensor for providing a signal indicative of engine
rpm.
13. An apparatus for determining whether the oil of an engine
requires changing, comprising: an engine control module having a
microprocessor; an oil temperature sensor adapted to provide an oil
temperature signal to an algorithm of said microprocessor; an oil
pressure sensor adapted to provide an oil pressure signal to said
algorithm; a sensor for providing a signal to the engine control
module, the signal being indicative of the rpm of the engine; a
look up table comprising data corresponding to used or fresh oil
viscosities as a function of at least one of the following
parameters oil pressure, oil temperature, and engine rpm; and a
means for indicating whether the oil viscosity is outside a
preferred range.
14. The apparatus as in claim 13, further comprising a means for
determining whether a relief valve of an oil pump of the engine is
closed.
15. The apparatus as in claim 13, further comprising a means for
determining whether the oil in the engine is in an unregulated
flow.
16. An oil change sensing system for an internal combustion engine,
comprising: an oil pressure sensor adapted to provide an oil
pressure signal to an engine control module; an oil temperature
sensor adapted to provide an oil temperature signal to said engine
control module; and a sensor for providing a signal to the engine
control module, the signal being indicative of the rpm of the
engine; wherein said engine control module comprises an algorithm
which determines the oil viscosity of new or fresh oil by measuring
two oil pressures at two different operating conditions after said
control algorithm determines the oil of the engine has been changed
and determines the oil viscosity of old or used oil by measuring
two oil pressures at two different operating conditions and
determines whether the oil is in a preferred range by comparing the
determined used or old oil viscosity with the determined new or
fresh oil viscosity.
17. The oil change sensing system as in claim 16, further
comprising a means for determining whether the oil of the engine
has been changed wherein the algorithm only determines the new or
fresh oil viscosity after said means has determined whether the oil
of the engine has been changed.
18. The oil change sensing system as in claim 17, further
comprising means for determining whether the oil in the engine is
in an unregulated flow.
19. The oil change sensing system as in claim 17, wherein the oil
viscosities are determined when the oil temperature is in a range
defined by a lower limit of 80 degrees Celsius and an upper limit
of 120 degrees Celsius.
20. The oil change sensing system as in claim 16, wherein the oil
viscosities are determined when the oil temperature is in a range
defined by a lower limit of 80 degrees Celsius and an upper limit
of 120 degrees Celsius.
21. A method for indicating whether the oil of an engine should be
changed, comprising: determining if the oil in the engine has been
changed and if so, determining the new oil viscosity by:
determining if the flow of the oil is unregulated, by measuring the
oil pressure and the oil temperature; measuring the oil pressure at
two different operating conditions (x) and (y) if the flow of the
oil is unregulated; determining a new oil viscosity; registering
the new oil viscosity; and determining if the oil in the engine has
a viscosity that is in a preferred range if the oil has not been
changed by: determining if the flow of the oil is unregulated, by
measuring the oil pressure and the oil temperature, the oil
pressure and the oil temperature being measured at two different
operating conditions (x) and (y); determining a used oil viscosity;
and using said used oil viscosity and said new oil viscosity to
determine whether the oil's viscosity is in a preferred range.
22. The method as in claim 21, wherein said new oil viscosity and
said used oil viscosity are determined when the oil temperature is
in a range defined by a lower limit of 80 degrees Celsius and an
upper limit of 120 degrees Celsius.
23. The method as in claim 21, wherein the two operating conditions
(x) and (y) are oil temperature and engine rpm, wherein engine rpm
and oil temperature are each measured by a sensor.
24. The method as in claim 22, wherein the two operating conditions
(x) and (y) are oil temperature and engine rpm, wherein engine rpm
and oil temperature are each measured by a sensor.
Description
TECHNICAL FIELD
The present disclosure generally relates to oil lubricating systems
of internal combustion engines and more particularly to a method
and apparatus for determining whether the oil of the engine
requires changing.
BACKGROUND
The present disclosure relates to an apparatus and method for
automatically indicating when to change the engine lubricating oil
by measuring the oil's viscosity. Traditionally, engine oil is
changed whenever the vehicle reaches a predetermined mileage, or a
specified time interval, which ever comes first. Under severe
operating conditions, however, the vehicle manufacturers may
suggest that the engine oil be changed more frequently.
These situations require the operator of the vehicle to make a
judgment as to when to change the engine oil. This judgment is
typically a guess, since the operator has no physical data on which
to base the judgment. Typically, degradation of the engine oil
occurs most rapidly at high and low temperature extremes. At high
oil temperatures, antioxidants in the oil tend to become depleted,
and the oil becomes more viscous and acidic due to oxidation. In
addition, insoluble particles are deposited on the engine surfaces.
At low oil temperatures, fuel, water and soot tend to accumulate in
the oil, reducing its viscosity and increasing wear.
Uncertainty of when to change the engine oil may result in changing
the engine oil more frequently than is necessary, which is a waste
of money, or not changing the oil frequently enough, resulting in
shortened engine life. "Good" oil has viscosity characteristics
sufficient to give good hydrodynamic lubrication of the loaded
surfaces, yet flows around the engine well enough to provide a
continuous supply of fresh lubricant. Therefore, oil viscosity is a
useful parameter for determining when the oil needs to be
changed.
SUMMARY
It is therefore a general object of the present disclosure to
provide a reliable and practicable system and method for
calculating and indicating when the oil of an engine needs to be
changed.
An oil change sensing system for an internal combustion engine,
comprising: an oil pressure sensor adapted to provide an oil
pressure signal to an engine control module; an oil temperature
sensor adapted to provide an oil temperature signal to the engine
control module; a sensor for providing a signal to the engine
control module, the signal being indicative of the rpm of the
engine; wherein the engine control module comprises an algorithm
which determines the oil viscosity of new or fresh oil by measuring
two oil pressures at two different operating conditions and
determines the oil viscosity of old or used oil by measuring two
oil pressures at two different operating conditions and determines
whether the oil is in a preferred range by comparing the determined
used or old oil viscosity with the determined new or fresh oil
viscosity.
A method for indicating whether the oil of an engine should be
changed, comprising: determining if the oil in the engine has been
changed and determining the new oil viscosity by: determining if
the flow of the oil is unregulated, by measuring the oil pressure
and the oil temperature; measuring the oil pressure at two
different operating conditions (x) and (y) if the flow of the oil
is unregulated; determining a new oil viscosity; registering the
new oil viscosity; and determining if the oil viscosity is in a
preferred range by: determining if the flow of the oil is
unregulated, by measuring the oil pressure and the oil temperature;
measuring the oil pressure at two different operating conditions
(x) and (y) if the flow of the oil is unregulated; determining a
used oil viscosity; using the used oil viscosity and the new oil
viscosity to determine whether the oil's viscosity is in a
preferred range.
An oil change sensing system for an internal combustion engine,
having an oil pressure sensor adapted to provide an oil pressure
signal to an engine control module; an oil temperature sensor
adapted to provide an oil temperature signal to the engine control
module; wherein the engine control module comprises an algorithm
which determines the oil's viscosity by using the measured oil
temperature and oil pressure and the determined oil viscosity and a
fresh oil viscosity are used to determine whether the oil is in a
preferred operating range.
A method for indicating whether the oil of an engine should be
changed by determining if the flow of the oil is unregulated, by
measuring the oil pressure and the oil temperature and measuring
the oil pressure and retrieving a used oil viscosity from a look up
table; and using the used oil viscosity and a fresh oil viscosity
to determine whether the oil's viscosity is in a preferred
range.
An apparatus for determining whether the oil of an engine requires
changing, comprising: an engine control module having a
microprocessor; an oil temperature sensor adapted to provide an oil
temperature signal to an algorithm of the microprocessor; an oil
pressure sensor adapted to provide an oil pressure signal to the
algorithm; a look up table comprising data corresponding to used or
fresh oil viscosities as a function of at least one of the
following parameters oil pressure, oil temperature and engine rpm;
and a means for indicating whether the oil viscosity is outside a
preferred range.
DESCRIPTION OF THE FIGURES
FIG. 1 is a schematic illustration of an oil lubrication
system;
FIG. 2 is a chart illustrating test results of oil temperature, oil
pressure and engine rpms measured with respect to time for a
particular vehicle and engine;
FIG. 3 is a chart illustrating test results of oil pressure, oil
viscosity and engine rpms measured with respect to oil temperature
for a particular vehicle and engine;
FIG. 4 is a chart illustrating the relationship between oil
pressure and oil viscosity for a particular engine, vehicle and
oil;
FIG. 5 is a chart illustrating the effect of viscosity on oil
pressure for a particular engine, vehicle and oil;
FIG. 6 is a flow chart illustrating a control algorithm for
developing a look up table during an initial oil viscosity
calibration stage for use in the method and apparatus of the
present disclosure;
FIG. 7 is a flow chart illustrating a control algorithm for
determining the oil's viscosity by taking oil pressure measurements
and using the look up table generated by the algorithm of FIG. 6;
and
FIG. 8 is a flow chart of an alternative algorithm to obtain oil
viscosity directly from two oil pressure measurements in real
vehicle operations.
DETAILED DESCRIPTION
Oil pressure is a measure of the oil's resistance to flow. In an
engine, oil pressure is a function of two factors: oil viscosity
and oil flow rate. Oil flow rate is a function of engine rpm and
oil flow regulation. Thus, for a constant engine rpm and without
oil flow regulation oil pressure is a function of oil viscosity.
Most new engines today use Gerotor pumps, which are a positive
displacement type of pump. For a given flow rate, the pressure
generated by the pump increases with oil viscosity. Flow rates of
the positive displacement type pumps are proportional to the speed
(rpm) of the oil pump. Since, the Gerotor pump speed is directly
proportional to engine speed, the flow rate is also proportional to
engine speed. For a given engine speed (rpm) such as idle, the oil
flow rate is nearly constant and the oil pressure is mainly a
function of oil viscosity. However, oil viscosity is very sensitive
to the temperature of the oil and decreases as the temperature of
the oil increases. Thus, the oil pressure at the pump tends to
decrease as the oil temperature increases. Conversely, as the oil
temperature decreases, oil pressure at the pump increases.
Therefore, by measuring the oil pressure and the oil temperature,
we can build the relationship between the oil viscosity and the oil
pressure.
An engine oil lubrication system is shown schematically in FIG. 1.
The system shown in FIG. 1 is for explanation purposes and is not
intended to limit the scope of the present disclosure.
Referring to FIG. 2 and in order to demonstrate and prove the
concept of the present disclosure, the oil temperature of a vehicle
engine was measured during warm-up (e.g., transitioning from a cold
start to normal operating temperatures and RPMS) using a
thermocouple inserted into the engine of a Buick Lesabre (2002
model year) with a 3800 V6 engine. This vehicle is equipped with a
dash display that shows oil pressure. The oil in the engine was
5W30, about one month old, and experienced about 1500 miles
driving. During 35 minutes of idling, the oil temperature increased
from 20.degree. Celsius to 100.degree. Celsius at an ambient air
temperature of 18.degree. Celsius. As shown in FIG. 2, the engine
rpm decreased from 1100 rpm to 730 rpm roughly after 7 minutes.
During this period the oil temperature increased almost linearly
with time. Also, the initial oil pressure was 69 psi, which
decreased slowly during the first 18-minutes and then decreased
rather rapidly.
The same test data are plotted as a function of oil temperature in
FIG. 3. As shown in FIG. 3, the oil pressure does not vary
significantly with changes in oil viscosity when the oil
temperature is less than 80.degree. Celsius. This is mainly because
the oil flow is regulated to prevent excessive pressure build up at
the oil filter assembly when the oil viscosity is high. The
regulation of the oil flow is provided by a relief valve, which is
opened to prevent excessive build-up in the system, for example in
the oil filter. When the oil temperature exceeded 80.degree.
Celsius at an idle speed, the oil flow rate became unregulated
wherein the relief valve was closed, and accordingly the oil
pressure was directly related to the oil viscosity. It is at this
point where the system and method of the present disclosure will
determine whether the oil of an engine requires changing by
measuring the viscosity.
The relationship between the engine oil pressure and the oil
viscosity (5W30, one month old and experienced about 1500 miles
driving) for oil at temperatures between 80.degree. Celsius and
100.degree. Celsius is shown in FIG. 4. A simple quadratic function
is sufficient to fit this data very accurately. From this
relationship, the effect of the oil viscosity on oil pressure can
be derived. As shown in FIG. 5, a -10% or +10% change of oil
viscosity is roughly equivalent to an oil pressure change of about
5 psi, or in other words, a 20% increase in the oil viscosity
results in roughly 10 psi increase of the oil pressure. As
mentioned above, the engine oil pressure is caused by the
resistance to the oil flow under pumping action. Besides viscosity,
any changes in the oil delivery system, such as pump efficiency,
oil galleries, and filtering performance, could also affect this
resistance and thus the measured oil pressure.
In order to avoid these effects of potential system changes on the
oil pressure measurements, we can also incorporate the measured
pressure difference at two different oil temperatures. Typically,
degraded old oil viscosity decreases faster with oil temperature
increase than the case for the fresh oil. This can be accomplished
by conducting the oil pressure measurement at two different
temperatures. Of course, oil pressure measurements can be made at
more than just two different oil temperatures.
In real vehicle applications, the oil pressure information is
utilized to estimate the viscosity of the engine oil when the oil
temperature is high enough (e.g., greater than (>) 80.degree.
Celsius as illustrated in the example of FIGS. 2-5) and at low
engine speed, such as idle. An algorithm for determining oil
pressure calibration with oil viscosity is shown in FIG. 6. The
actual viscosity measurement procedure used in vehicular or other
dynamic applications is shown in FIG. 7.
Referring back to FIG. 1, an oil indicator system 10 for a diesel,
gas, or other equivalent internal combustion engine is
schematically illustrated. The system includes a microprocessor or
electronic controller 12 for processing sensor input data and
generating an output. The electronic controller of the oil
indicator system may be integrally combined or closely associated
with the Electronic Control Module (ECM) that is conventionally
provided on most modem diesel or gasoline engines, or may
alternatively be a separate component from the ECM.
The electronic controller includes an input in electrical
communication with a plurality of sensors for sensing or
determining a plurality of oil operating parameters. As an
alternative, the sensors may be in wireless (RF) communication with
the controller. Of course, other equivalent means of communication
are considered to be within the scope of the present disclosure.
Such parameters may include oil pressure and oil temperature that
are generated in the oil circulation system and are used to provide
the required information. For example, an oil pressure sensor 14
and an oil temperature sensor 16 are disposed to provide readings
of the oil as it circulates through the system. It will be
appreciated to those skilled in the art that these oil sensors may
be preexisting or already provided on conventional newly built
engines wherein the sensors are in communication with the ECM and,
in order to implement the method of the present disclosure,
additional software is only added to the microcontroller. Of
course, and in other applications the required sensors are
positioned within the oil circulation system.
The oil circulation system schematically illustrated in FIG. 1 also
includes an oil sump 18 wherein oil 20 circulated or pumped through
the system via an oil pump 22 fluidly connected with the sump and
an oil filter 24. As discussed above the oil circulation system
includes a pressure relief valve 26 that is in fluid communication
with the oil pump and the oil sump wherein the relief valve is
calibrated to prevent excessive oil pressure build up within the
oil circulation system. In order to prevent excessive build up of
oil pressure the relief valve opens and the oil flow is regulated.
The oil as indicated by the arrows in FIG. 1 is pumped to the oil
galleries 28 of an internal combustion engine 30 thereby
lubricating the moving part of the engine. Accordingly, the oil is
circulated through the engine in accordance with known
technologies.
Referring now to FIGS. 2-6, the creation of a look-up table for use
in an algorithm and system (FIG. 7) resident upon a microprocessor
of a vehicle is illustrated. Again, and as discussed above, the
quadratic formula of FIG. 4 is determined when the flow and
pressure of the oil is unregulated (oil pressure relief valve
closed) see also FIGS. 2, 3 and 5. FIG. 6 illustrates an algorithm
40 for a procedure to develop a look up table during the initial
viscosity calibration stage. It is noted that this procedure can be
performed for numerous engine types (e.g., 4, 6, 8 and 12 cylinder
engines) of varying sizes, each having varying performance
standards as well as oils of different weight and type (synthetic,
non-synthetic or mixes, blends etc.). Accordingly, individual look
up tables can be generated for engine types as well as oil types.
Thus, the look up table will have a sufficient amount of data to
provide a means for determining whether the oil requires changing
when it is measured by a system in accordance with the present
disclosure. The look up table is generated in a laboratory
environment wherein it can be tested and ultimately validated for
use in a system of a vehicle or other item having an internal
combustion engine and an engine control module or equivalent
thereof.
As an alternative to the look up table generation in a laboratory
environment and in an alternative embodiment (FIG. 8), a similar
relationship is created between the fresh oil viscosity and the oil
temperature. In this embodiment, the entire process takes place in
the vehicle being driven right after an oil change and every day
thereafter. This procedure can be performed either in a laboratory
environment or during actual vehicle driving conditions. The
detailed procedure is described in FIG. 8.
Referring back now to FIG. 6, algorithm 40 is initialized at block
42 when a new engine is started with new oil. At block 44 the
algorithm will determine when the engine is warmed up to the point
that the oil pressure is in an unregulated state (e.g.,
corresponding to the relief valve of the oil pump being closed)
thus, the oil pressure measurements are directly related to the oil
viscosity. Step or block 44 determines that the oil pressure relief
valve is fully closed by measuring the oil temperature or other
parameter, which will indicate whether the engine is in a state
where the pressure relief valve will be closed. This can also be
determined by knowing the operational parameters of the oil pump
and valve (provided by the manufacturer) or by directly measuring
the position of the pressure relief valve though the use of a
sensor appropriately positioned to determine the position of the
valve (e.g., open or closed) and provide the sensed information
back to the microcontroller. Once this is determined by block 44,
the engine speed is fixed at low rpm (revolutions per minute) by
block or step 46 of the algorithm. If not, algorithm 40 remains at
step 44 until the pressure relief valve is fully closed.
Once step or block 44 determines that valve is fully closed (oil
pressure being unregulated), step or block 46 will fix the engine
speed at a predetermined point and the algorithm will advance to
step or block 48 wherein the oil pressure is measured and the
corresponding oil temperature and engine speed is also recorded.
Once this data is recorded the algorithm at step or block 50
increases the engine rpm incrementally. For example, step 50 could
use the following formula (x(rpm)=x(rpm)+y(increment)) wherein
x(rpm) is the engine speed and y(increment) is the incremental
increase.
Next, a decision node 52 determines whether the upper range of the
fixed engine speed has been determined. Accordingly, the loop of
steps 46, 48, 50 and 52 is repeated until all of the desired data
points are recorded. For example, in the example illustrated in
FIG. 6, the fixed engine speed is defined by the range between 700
and 1500 rpm. Of course, it is contemplated that the range may
include values greater or less than the aforementioned values.
Accordingly, and in the example provided once the engine rpm has
been increased to a value greater than 1,500 rpm algorithm 40
advances on to step 54. At step 54 data for a look up table for the
engine oil is generated based upon a reference oil property .mu.(T)
(viscosity as a function of temperature, which is provided by the
oil manufacturer or alternatively a relative oil property
.mu..sub.old (T)/.mu..sub.new (T) for the fresh oil and the used
oil can be evaluated from oil pressure measurements during various
vehicle driving conditions when the oil pressure relief valve is
closed. The detailed procedures of this embodiment are described
and illustrated in FIG. 8) and the measured oil pressures as a
function of temperature and engine rpm thus, pressure (P) is a
function of oil temperature (T) and engine rpm (rpm). Accordingly,
P(T, rpm).
In accordance with the example provided in FIGS. 2-6 the following
quadratic equation was developed:
wherein y=oil pressure and x=oil viscosity and R.sup.2 =0.9999
wherein R.sup.2 represents the coefficient of determination which
is the strength of association or degree of closeness of the
relationship between two variables measured by a relative value.
Thus, the value of R.sup.2 =0.9999 indicates that the quadratic
formula is very accurate or the standard of error is very
small.
Once the algorithm of FIG. 6 determines the required data for a
look-up table for a given engine and oil, the data is available in
a transferable format which can be stored in the non-volatile or
read only memory of a programmable microprocessor, which is then
used in accordance with the present disclosure to determine whether
the oil of an engine needs to be changed.
Referring now to FIG. 7, a flow chart 70 of an algorithm for use in
a microcontroller of a vehicle (e.g., engine control module ECM) is
illustrated. The algorithm in accordance with the present
disclosure will determine whether the oil of the vehicle's engine
requires changing. The algorithm is provided with a look up table
which comprises the data obtained by the algorithm and procedure
shown in FIG. 6. Of course, the look up table will include data
which is specific to the type of engine and oils contemplated for
use with the engine and/or vehicle type.
A first step represented by block 72 determines whether the
vehicle's engine is on. This can be determined by any means known
to one skilled in the art wherein a signal indicative of a running
engine is provided to the engine control module. Once the algorithm
determines whether the engine is running, a step represented by
block 74 determines whether the engine has recently had an oil
change and if this is the first time the engine has been started
since the oil change. Block 74 determines whether there has been an
oil change through the receipt of a signal from a reset button (not
shown) which is manipulated after the oil change. The reset button
is currently a standard feature on some of today's production
vehicles. Other methods and means for determining and providing a
signal indicative of a new oil change may comprise and are not
limited to the following: a smart sensor disposed within the oil
sump which will determine whether the oil level has dropped
dramatically (e.g., consistent with an oil change) or
alternatively, a sensor that measures viscosity and provides a
signal of a large oil viscosity change. Of course, other sensors
and methods, known to individuals skilled in the art for providing
a signal indicative of an oil change are contemplated to be within
the scope of the present disclosure.
If block 74 determines that there has been an oil change in the
engine, a step or block 76 determines whether the engine oil
pressure is unregulated (e.g., relief valve of oil pump closed).
This is determined at block 76 by measuring the oil pressure and
oil temperature of the oil by oil temperature and pressure sensors
appropriately positioned to provide such readings to the algorithm
of the present disclosure. Alternatively, other means for
determining whether the relief valve is closed may be used in
accordance with the algorithm of FIG. 7. Once step 76 determines
that the oil flow is unregulated, the oil pressure is measured and
registered into the look up table of the control algorithm by a
step represented by block 78. As mentioned above, the measured oil
pressure has a direct correlation with respect to the temperature
of the oil and the rpm of the engine into which the oil is located.
If on the other hand block 76 determines that the relief valve of
the oil pump is still open (regulated flow), block 76 continues to
measure the oil pressure and the oil temperature until an
unregulated flow (relief valve closed) is detected.
Once block 78 registers the measured oil pressure, step or block 80
obtains the corresponding fresh oil viscosity .mu..sub.o from the
look up table. As previously noted, this information is stored in
the look up table through the analysis and methods illustrated in
FIGS. 2-6 and the readily available data sheets provided by the
manufactures of specific oil types, which is all stored in the look
up table of algorithm 70.
Once the fresh oil viscosity .mu..sub.o of the new oil is obtained,
it is stored in the look up table at step or block 82. The fresh
oil viscosity is now stored in the algorithm as a constant for use
in the system. It is also noted that the steps or loop outlined by
block 84 (dashed lines) are only performed once and only after
block 74 determines whether a new oil change has taken place.
In the event that block 74 determines that a new oil change has not
taken place, step or block 86 determines whether the engine oil
pressure is unregulated (e.g., relief valve of oil pump closed).
This is determined at block 86 by measuring the oil pressure and
oil temperature of the oil by temperature and pressure sensors
appropriately positioned to provide such readings to the algorithm
of the present disclosure. Once step 86 determines that the oil
flow is unregulated the oil pressure is measured and registered at
step or block 88. As mentioned previously during unregulated oil
flow, the measured oil pressure has a direct correlation with
respect to the temperature of the oil and the rpm of the engine
into which the oil is located.
If on the other hand block 86 determines that the relief valve of
the oil pump is still open (regulated flow) block 86 continues to
measure the oil pressure and the oil temperature until an
unregulated flow is detected.
Turning back now to block 88, once the oil pressure is measured,
the used oil viscosity .mu. is obtained at step or block 90 from
the look up table generated by the algorithm of FIG. 6, or
alternatively, the aforementioned quadratic formula is used to
determine the used oil viscosity. Once the calculations or
comparison of block 90 is complete, step or block 92 compares the
used oil viscosity .mu. with the fresh oil viscosity .mu..sub.o by
for example, dividing .mu. by .mu..sub.o At this point, the
algorithm advances to step or block 94 wherein it is determined
whether the compared viscosities are within a predetermined ranged
defined by a lower constant C1 and an upper constant C2. If the
compared values are outside the range defined by C1 and C2, an oil
change signal 96 is generated; otherwise, a non-oil change signal
98 is generated.
Upon receipt of an oil change signal the electronic controller
provides an output connected to a display (not shown), which may be
an LED signal device or other appropriate display means that is
preferably in view of the engine operator, such as in the cab of a
vehicle.
The electronic controller utilizes the algorithm which collects
data from the sensors and the look up table to periodically
determine if the oil needs changing.
A "change oil" warning signal can thus be sent to the vehicle
operator when the viscosity estimated at a given oil temperature
and engine speed exceeds a predetermined "threshold". It is noted
that in accordance with the present disclosure the oil pressure
read out is an existing feature readily available on some current
production vehicles. Thus, there is no need to add an oil pressure
sensor to implement the system of the present disclosure.
A similar concept can be applied to lower end vehicles equipped
with an oil pressure switch in place of an oil pressure readout. By
calibrating the oil pressure level switch point, monitoring engine
speed through one of various means, and measuring the oil
temperature at the oil pressure switching point, the corresponding
oil viscosity can be estimated. The basic concept of utilizing the
oil pressure readout or the oil pressure switch to estimate the oil
viscosity and the need to change oil is not limited to automotive
applications. It can be applicable to all power generating
equipment that utilize a fluid, such as oil, as a lubricating
method.
Referring now to FIG. 8, an alternative embodiment of the present
disclosure is illustrated. Here components performing similar or
analogous functions are numbered in multiples of 100. However, at
the outset it is particularly noted that steps 178, 180, 188 and
190 are significantly different from steps 78, 80, 88 and 90 of the
FIG. 7 embodiment as will become readily apparent in view of the
discussion of FIG. 8 below, as well as FIG. 8 itself.
The detailed procedure to generate a look up table for oil
property, .mu.(T), was described previously. In this embodiment,
the approach is to measure directly the oil viscosity, .mu.(T),
during various vehicle operating conditions. As described above,
the oil pressure relief valve is closed during low engine rpm and
also when the oil temperatures are relatively high, for example,
above 80.degree. C. (a Buick Lesabre). The engine operating
conditions that we are interested in in the present application
occur when the oil temperature is in the range between 80.degree.
C. and 120.degree. C. In this range, the oil viscosity decreases
almost linearly with oil temperatures and we can approximate the
oil viscosity, .mu.(T), as:
The constants A' and B' vary as the oil degrades during vehicle
operations.
The oil flow conditions in oil galleries are typically laminar
flows and oil density is nearly constant for the oil temperature
range between 80.degree. C. and 120.degree. C. that we are
interested in. For a laminar flow in a channel flow, the total
pressure drop is linearly proportional to the product of the oil
flow rate and the oil viscosity. Thus, the oil flow rate of the
positive displacement type pumps is proportional to the speed (rpm)
of oil pump. Since, the oil pump speed is directly proportional to
engine speed, the oil flow rate is also proportional to engine
speed. Therefore, the oil pressure, P, can be described as:
where K is a constant for a given engine, which depends, only on
the geometry of oil galleries and A and B are oil property
constants defined as
The oil property constants (A and B) can be determined from two
measured data points during vehicle operations when the oil relief
valve is closed. The measured data includes the engine speed (rpm),
the oil temperature (T), and the corresponding oil pressure (P).
From Equation (2), we can determine A and B for fresh oil and used
oil if we monitor oil pressures at two different operating
conditions each for the fresh oil and the used oil. The algorithm
for this procedure is described in FIG. 8. In order to determine
the constant A and B, we need only two data points. However, in
order to generate more reliable constants A and B for the oil
viscosity model (Equation (1)), we can monitor the oil pressures at
more than two operating conditions and we can evaluate or optimize
the constants A and B by least square fit of the multiple data
points during vehicle operations when the oil relief valve is
closed. This procedure described herein, does not require any
special corrections or modifications due to oil type or engine
type. The algorithm (as shown in FIG. 8) is universal to any oil
type and engine type and does not need any additional steps to
generate a look up table, which was described in FIG. 6. This
algorithm eliminates the step for a look up table generation in a
laboratory environment for each engine family.
Referring now to FIG. 8, a flow chart 170 of an algorithm for use
in a microcontroller of a vehicle (e.g., engine control module ECM)
is illustrated. The algorithm in accordance with the present
disclosure will determine whether the oil of the vehicle's engine
requires changing.
A first step represented by block 172 determines whether the
vehicle's engine is on. This can be determined by any means known
to one skilled in the art wherein a signal indicative of a running
engine is provided to the engine control module. Once the algorithm
determines whether the engine is running, a step represented by
block 174 determines whether the engine has recently had an oil
change and if this is the first time the engine has been started
since the oil change. Block 174 determines whether there has been
an oil change through the receipt of a signal from a reset button
(not shown) which is manipulated after the oil change. The reset
button is currently a standard feature on some of today's
production vehicles. Other methods and means for determining and
providing a signal indicative of a new oil change may comprise and
are not limited to the following: a smart sensor disposed within
the oil sump which will determine whether the oil level has dropped
dramatically (e.g., consistent with an oil change) or
alternatively, a sensor that measures viscosity and provides a
signal of a large oil viscosity change. Of course, other sensors
and methods, known to individuals skilled in the art for providing
a signal indicative of an oil change are contemplated to be within
the scope of the present disclosure.
If block 174 determines that there has been an oil change in the
engine, a step or block 176 determines whether the engine oil
pressure is unregulated (e.g., relief valve of oil pump closed).
This is determined at block 176 by measuring the oil pressure and
oil temperature of the oil by oil temperature and pressure sensors
appropriately positioned to provide such readings to the algorithm
of the present disclosure. Alternatively, other means for
determining whether the relief valve is closed may be used in
accordance with the algorithm of FIG. 8. Once step 176 determines
that the oil flow is unregulated, the oil pressure is measured and
registered at two different operating conditions, as mentioned
above with regard to equations 1 and 2, by a step represented by
block 178. As mentioned above, step 178 is significantly different
than the algorithm of FIG. 7.
If on the other hand block 176 determines that the relief valve of
the oil pump is still open (regulated flow), block 176 continues to
measure the oil pressure and the oil temperature until an
unregulated flow (relief valve closed) is detected.
Once block 178 registers the two measured oil pressures at two
different operating conditions, step or block 180 calculates the
constants A.sub.new and B.sub.new of the fresh oil (e.g., oil
change has just occurred) using equation 2 above. Once this has
occurred, block 180 obtains the fresh oil viscosity using equation
1 above and the new constants A.sub.new and B.sub.new of the fresh
oil. Thus, step 180 is able to determine the fresh oil viscosity
without need for generating a look up as described with regard to
FIG. 6. Accordingly, steps 178 and 180 use equations 1 and 2 to
ultimately determine the fresh oil viscosity.
Once the fresh oil viscosity .mu..sub.new of the new oil is
obtained, it is stored or registered at step or block 182. The
fresh oil viscosity is now stored in the algorithm as a constant
for use in the system. It is also noted that the steps or loop
outlined by block 184 (dashed lines) are only performed once and
only after block 174 determines whether a new oil change has taken
place.
In the event that block 174 determines that a new oil change has
not taken place, step or block 186 determines whether the engine
oil pressure is unregulated (e.g., relief valve of oil pump
closed). This is determined at block 186 by measuring the oil
pressure and oil temperature of the oil by temperature and pressure
sensors appropriately positioned to provide such readings to the
algorithm of the present disclosure. Once step 186 determines that
the oil flow is unregulated, the oil pressure is measured and
registered at two different operating conditions as discussed above
with regard to equations 1 and 2.
If on the other hand block 186 determines that the relief valve of
the oil pump is still open (regulated flow), block 186 continues to
measure the oil pressure and the oil temperature unit an
unregulated flow is detected.
Turning now to block 188, once the oil pressure is measured, the
used oil viscosity .mu..sub.old is obtained at step or block 190
using results of block 188 as well as equations 1 and 2 described
above. Once the calculations of block 190 are complete, step or
block 192 compares the used oil viscosity .mu..sub.used (determined
at block 190) with the fresh oil viscosity .mu..sub.new determined
by for example, dividing .mu..sub.old by .mu..sub.new. At this
point, the algorithm advances to step or block 194 wherein it is
determined whether the compared viscosities are within a
predetermined ranged defined by a lower constant C1 and an upper
constant C2. If the compared values are outside the range defined
by C1 and C2, an oil change signal 196 is generated; otherwise, a
non-oil change signal 198 is generated.
Upon receipt of an oil change signal, the electronic controller
provides an output connected to a display (not shown), which may be
an LED signal device or other appropriate display means that is
preferably in view of the engine operator, such as in the cab of a
vehicle.
The electronic controller utilizes the algorithm which collects
data from the sensors and the look up table to periodically
determine if the oil needs changing.
A "change oil" warning signal can thus be sent to the vehicle
operator when the viscosity estimated at a given oil temperature
and engine speed exceeds a predetermined "threshold". It is noted
that in accordance with the present disclosure the oil pressure
read out is an existing feature readily available on some current
production vehicles. Thus, there is no need to add an oil pressure
sensor to implement the system of the present disclosure.
Accordingly, the algorithm of the FIG. 8 embodiment does not
require the generation of a viscosity look up table (FIG. 6) as the
viscosity is determined by the software in real time with regard to
vehicle conditions.
While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the present disclosure not be
limited to the particular embodiment disclosed as the best mode
contemplated for carrying out this invention, but that the
invention will include all embodiments falling within the scope of
the appended claims. Furthermore, no element, component, or method
step in the present disclosure is intended to be dedicated to the
public regardless of whether the element, component, or method step
is explicitly recited in the claims.
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